2012 Chevrolet Malibu - Manifold and burned valves

cracked exhaust manifold repair turns into burnt valves and a new motor? Took my mothers car in for a new exhaust manifold, and they told me the codes come back to burnt valves showing the car basically needs a motor replacement at around 105k miles… really wondering if im being taken for a ride…

Then have it towed to another shop to get a second opinion. With a job this expensive, a $100 tow is nothing. If you don’t TRUST the shop, why spend money (BIG money) there??

Wondering if running car to long with a cracked exhaust manifold could cause exhaust valves to burn. Someone know?